Bottom icing refrigerator



1937. G. H. MEINZER 2,089,566

BOTTOM I CING REFRIGERATOR F|G.5. FIG.

INVENTOR.

l GOTTHOLD HA YME ZER 1937- G. H. `MEINZER 2,089,566

BOTTOM ICING REFRIGERATOR Filed July l, 1935 4 Sheets-Sheet 4 FIG. IO':

INVENTOR.

A RNEY.

'GOTTHOLD RRY M INZER Patented Aug. 10, 1937 UNITED STATES PATENT OFFICE signor to California Consumers Corporation, Los Angeles, Calif., a, corporation of California Application July i, 1935, Serial No. 29,418

10 Claims'.

The primary object of my invention is to pro- Vide a refrigerator of the type on which the cooling' efiect is produced by the melting of a solid such as ice, in which the cooling solid is placed in the bottom 'of the cooled compartment.

A further object of my invention is to provide a refrigerator of the class described which is adapted to the use of solid bodies. other than water ice, such for example as solid carbon dioxide or so called dry ice.

It is well known that in the class of refrigerators which are cooled by the melting of ice, the ice is always placed in the top of the refrigerator. The obvious reason for this procedure is 5 that cold air is heavier than that which is warmer and that therefore the cooling effect must be applied at substantially' the top of the vessel to be cooled in order to produce the circulation by which the cooling efiect is equalized throughout go the Vessel.

This requirement has been a serious drawb'ack to the use of iced refrigerators, for several rea- Sons. First, and particularly in large units, the ice has to be lifted to a relativ'ely high level and 5 lowered into the ice compartment by a xv ment which is essentially awkward and dificlt. Second, the ice compartment must be eparted from the storage compartment of the refriger'- ator by a heat transmitting partiti which is gb almost of necessity fr'ail and little dfited to support the weight of ice which rests on it. Third, this partition is immediately above the food compartme nt and any le'kg' through or around the partiton tends to drop into articles stored in this compartment. i

For these reasons", as wen' as others of less importance, the provisin of a refrigerator' which could be' iced below iiste'ad of above the food compartment has long' been desired', and many 4-*0 attempts have been made to provide such' a device' in a workable form. It is vident that the thermo-syphon prihciple is not applicabl for the tras'mission ei heat from the top of a Vessel to a heat-absrbin agent at the bottom, and

45 th previous attempts' to equalize the tempera tre have heer'i confired, so far as I know, to me'chaiical devices such as' fans for producin'g air ifculation. These devices' are" fully finctioral and' are dsrable for large" installations 50 but' are hardlyafplic'ble to' household refrigerators r' other sm'all u'nits.

My invention comprises means for withdrawing' heat froni the up'p'er or uppermost portion of a' storage compartmen't and for transmitting 55 that heat to' the' cooling medium placed substantially below the storage compartnent ad, in certain modified forms of the invention, means for controlling the rate at which the he'at is transmitted. By the first named means a cooling efiect whih is' initiated at the bottom of the 5 chamber is exercised at any desired location in the upper part of the chamber and, as the air thereby cooled tends to move downwardly in the storage space, the temerature within that space is automatically equalized By the second ramed 10 means any desired temperature clifierence between the heat-absorbing element i the tap of the storage space and the colin medium in the bottom thereof may be maintained, and thus it becomes possible to utilize cooling' media such as dry ice which by unrestrained evapcration produce temperatures far below those which can be tolerated ina refrigerator;

The 'various features of the inventio may best be explained with reference to the attached drawings' and the fllowng description thereof, in which Fig. 1 illustrate in cross section and partial elevation, as on the line l-I of Fig. 3, a modification of the irvention adapted to the use of water ice;

Fig. 2 illutrates in the same marinar' and as on the line 2-2 of Fig. 4, another modification adapte'd to the use of water ice;

Fig. 3 is a plan section on the line 3-3 of Fig. 1;

` Fig. 4 is a plan section on the line 4-4 of fl- 2; u i

Fig. 5 is a cross section through a modification of the invention adapted to the useof solid car- 3 bon dioxide, as on the line 5- 5 fFig. 7;

Fig. 6 is a section illustrating the same modification, taken on the line 6-6 of Fig'. 5;

Fig. '7 is a section illustrating the same modification, taken on the line l-'I of Fig. 5; 40

Fig. 8 is a section similar to Fig. 5 but illustrating a modified manner of insulating the carbon dioxide container;

Fgs. 9 to 14, inclusive, are details illustrating preferred means for controlling the flow of heat from the heat-absorbing element to the carbon dioxide container. h

Referring first to Figs. 1 and 3, ID is an outer and ll an inner casing of metal, enarneled metal or other suitable material separated by' a relatively thick layer of low. temperature insulating material IZ, a suitable insulated door of substantially the same materials being provided but not shown. This door forms a portion of one 55 of the vertical walls of the refrigerator, as is conventional and as indicated at 81 in Fig. 6.

In the lower part of the box thus formed I place a supporting screen i 3 on which ice may be placed as required. This screen is formed of stiff and relatively closely woven heavy wires of a heatconductive metal as for example aluminum or copper and may rest on supports indicated at !4 to permit drainage of melt into a drain pipe !5. It is desirable though not Strictly essential to rmly fix the ends of the wires composing the M screen in an edging strip [6 of the same metal in such manner that heat conduction -to the screen Will not be interfered With by films of oxides or other corrosion products. A similar screen l'l is supported in the upper portion oi 'the box by means of standards !8-!8 formed' of heat-conductive metal, the standards' being brought into heat-conductive relation with the edging strips or with the screen itself, 'as for example by the threaded studs |9 and the nuts 28, or by riveting or merely by soldering. If a pressural contact is made, it may be desirable to prevent corrosion which might reduce the efficiency of the contact by dipping the entire assembly in a molten metal such as tin or Zinc and thus scaling all the joints against the intrusion of moisture.

It is also desirable, though again not strictly necessary, to insulate the heat-conductivestandards !8-!8 'against transfer of heat from or to the air within the box, in order to maintain the greatest possible temperature difierence between the screenll at the top of the box and the screen !3 on which the ice rests. Such insulation is indicated at 2! in Figs. 1 and 2.

When a cooling medium' such as ice is rested on the lower screen 13, the metal of the screen is cooled to the temperature of melting ice, or close to 32' F., and the temperature of the upper screen H is rapidly reduced by the conduction of heat to and through the metallic rods !8, to and through the edging strips !6 and finally through the lower screen !3 `to the ice, which melts without rising in temperature. whenever the temperature oif the upper screen falls below the temperature of the immediately surrounding air, heat is transmitted from the air to the upper screen and through the same course to the ice. By providing sufficient areas in the conductive rods and taking reasonable precautions to see that the joints are fully conductive, the temperature of the upper screen may be maintained within not over 2 F. and in favorable casesaslittle as 1 F. above that of the lower screen.

The air thus cooled being heavier than the warmer air in the body of the box, convection currents are set up by which heat is constantly transmitted to the upper screen, to be removed by conduction as above described, and in this manner the air in the box may be reduced in temperature at substantially the same rate as it would be reduced by contact with a block of ice placed in the upper part of the box and having no greater superficial area than that of the upper screen. In fact it is possible to effect the cooling by the described means at an increased rate, if the sur- .face of the screen be blackened as by the oxidation of copper, such blackened surfaces absorbing heat more freely than the reflective surface of an icecake. V

The above device is subject to 'several modifications, certain of which are illustrated in Figs. 2

and 4.- Thus, the lower screen or the upper screen or both may be replaced by the parallel use of very low temperature refrigerants such as solid carbon dioxide (the so-called dry-ice) is illustrated in Figs. 5 to 14 inclusive.

In Figs. 5 to 7, inclusive, i@ and H are outer and inner shells respectively and !2 is a thick layer of low temperature insulating material. In some preferred portion of this bed of insulation, illustrated as being the lower portion, I place a gas tight receiver for holding a supply of dioxide, this receiver consisting of a thick walled metallic case 48, closed at one end and provided at the opposite end with a coarse screw thread 4! and a threaded plug 42. The plug should be formed of heat insulating material (e. g., a shell of molded synthetic resin filled with cork) and should eX- tend to the exterior of the outer shell so that it may be removed without opening the door of the refrigerator. The case 40 shouldbe of some heatconductive metal such as Copper.

To the closed end of the case are .attached a plurality of risers 43, in the form of solid copper or aluminum rods. All of these risers are joined' in a heat-conductive manner to thewall of the case and at their upper ends to an equalizing bar M of the same metal. To this bar are similarly attached a pluralityof horizontal conductive rods 45 which pass through the inner shell (preferably without Contacting with it and extend across the upper part of the space within the inner shell. These rods may be provided with the fins 45 if desired.

The gas evolved by evaporation of the solid dioxide is at a very low temperature and is capable of absorbing considerable heat. This refrigerating Value may be recovered by providing a chamber 41, the lower wall of which comprises a portion of the inner shell Il and is in contact with the air within the refrigerator. This chamber` is Vented as at 48 and a tube 99 leads from the interior of the receiver 40 into the opposite end of chamber M. This chamber may be pro- Vided with internal baffles to cause the gas to make a circuitous course and to come to substantially the temperature of the air with which the lower wall of the chamber is in contact before it is vented. The vent 48 may desirably be provided with either an outwardly opening check valve or a dessicating trap, not shown, to prevent atmospheric moisture from entering and forming frost in the chamber.

As it is absolutely essential to restrain atmospheric heat from penetrating to receiver 40, I prefer to first pass the evolved gas through the insulating shell indicated at 50 in Fig. 8. The gas evolved in the receiver passes into this shell through a tube 5! and is directed by the helical fin 52 in a circuitous course through the shell, finally passing out through tube 49 to chamber i? as above described. If this shell is separated from the receiver by a sufilcient layer 52 of insulating material, any atmospheric heat which may penetrate the layer of insulation surrounding the shell will be almost totally absorbed in slightly warming the gas,- and' this heat will therefore be substantially prevented from penetrating to the wall of the receiver and-causing' an undesired evaporation of the solid dioxide.

When solid carbon dioxide is placed in the receiver 48 and the plug 42 inserted, carbon dioxide gas is rapidly evolved and passes through tube 49 into chamber 41 and thence to the outer air. By this evaporation of the solid dioxide the case itself and the insulating material immediately surrounding it are rapidly brought to a very low temperature, approximating the boiling .point of carbon dioxide or -79 C'.

If there were no passage of heat into the rods 45, the entire metallic' assembly of case 40, risers 43, bar 44, and rods 45 would soon attain the same temperature and, assuming that leakage of heat into the case is substantially prevented, -evaporation of the dioxide would cease because of lack of heat supply.

This, of course, does not take place, as heat is transmitted from the air in the upper portion of the refrigerator to the rods 45 and from them is conducted in the reverse direction through the above named metallic assembly, to be finally absorbed in evaporating further quantities of the dioxide. It will be evident, then, that if we can control the flow of heat from the air within the refrigerator to the carbon dioxide within the case,-we can fully control the rate at which refrigeration of the air is effected, and it will further be evident that this control may be efiected either at the point where heat is transmitted from the air to the rods 45 or Somewhere along the system by which this heat is passed on to the receiver 40.

The lack of relationship between rate of heat transmission and ultimate temperature of refrigeraticn should be kept clearly in mind. No matter how low the transmission rate, a permanently closed refrigerator will ultimately attain that (usually close) approach to the evaporating temperature of the refrigerant at which the transmission of heat from the internal air to the refrigerant just balances the transmission of heat through the refrigerator wall from external to internal air.

It is therefore theoretically impossible to control the ultimate temperature by any fixedtcontrol of the transmission rate, that is, by any control which is not directly responsive to temperature, changes within the refrigerator. None the less it is highly desirable to be able to effect a relatively fixed or manual control of the transmission rate in order to bring it into an approximate balance with the heat input to an individual refrigerator under the conditions obtaining in its use and under varying climatic conditions. such Controls avoid too great a heat head between internal air and absorbing rods, which tends to produce an undesirable temporary supercooling,

and also avoids excessive hunting of a heat responsive device. In cases where a refrigerator is in constant use and opened at fairly regular intervals, as in large commercial installations, such manual controls may function without temperature responsive devices within safe temperature limits if the transmission rate be sharply reduced prior to periods of iclleness.

For exercising a manual control of the transmission rate from rods 45 to receiver 40 I pro- 7 vide means for selectively interrupting the flow of heat through individual risers 43. Thus, as in Figs. 9 and 10, an opening BG is found through the outer shell I@ at such point as to expose rods 43 at some location where they are close together,

an insert plug 6! of insulating material being provided to close this opening. Within this opening one or more of the risers is broken as at 62 and each end threaded as at 63, one of these threads being relatively long. On the long thread is placed an internally threaded connector 64, shown in detail in Fig. 11, the threaded ends of the riser sections being so spaced that this Connector may be run down to form a firm contact with the lower section without passing off of the upper thread. If all of the risers are similarly provided, the flow of heat may be interrupted completely or may be regulated by as many steps as there are individual rods. The particular device shown in these figures is intended to be illustrative only as it will be evident that many other means could be used for making and breaking the heat conductivity of the risers, or that such devices might alternatively be applied to the rods 45.

The transmission rate may also be manually controlled by regulating the fiow of heat from the internal air to the heat-absorbing means such as the fins 46 and/or rods 45. For illustration, the sleeves lil-'H-TZ of Fig. 12 may be arranged to telescope so as to cover only a short section of the rod or to be drawn out as shown in the figure to cover a part or all of the rod and ns, thereby stopping the flow of air over the rods, which is normally produced by convection Currents. such devices, again, are subject to a wide variation in form.

The necessity for manual control may be avoided and the minimum temperature in the refrigerator automatically controlled by providingtemperature responsive means for breaking the continuity of the heat-conductive system. A simple device for this purpose, which might have many mechanical variants, is illustrated in Figs. 12 and 13.

`In these figures, one or more of the rods 45 is interrupted by the interposition of a nonoonductive block of some rigid material such as a molded synthetic resin. The ends of the interrupted rods are firmly fixed in this block as at 'Bl-Bl and one rod section (ordinarily that within the refrigerator) is given a free support to prevent the'destruction of the block by expansion and contraction due to temperature changes.

In the center of the block is formed a well 82 into which' the rod ends project, leaving a relatively narrow space 83. The well communicates through this space and a connecting tube 84 with a mercury bottle 85 placed in any part of the refrigerator in which it is desired to control the temperature. The bottle and the channel above described are filled with mercury and the quantity so adjusted that when the desired minimum temperature is reached the upper end of the mercury column will be at or slightly above the level indicated at 86, the heat-conductive connection between the rod ends being then almost or quite broken. As the temperature rises above this desired minimum, the resultant expansion of the mercury causes it to fill the space 83 and restore the heat-conduction connection. The Volume of mercury in the bottle should bear such relation to the capacity of space 83 that the space will be completely filled and the heat conductivity fully restored' in response to a temperature rise of only a few degrees. On account of the relatively low heat conductivity of mercury it is desirable that the space between the rod ends should be narrow.

I claim as my invention:

1. A refrigerator comprising: a receptacle insulated to exclude atmospheric heat; a metallic, heat-conductive support for a solid 'refrigerant located at substantially the bottom of said receptacle; a wholly metallic heat-absorbing' element substantially horizontally arranged adjacent the upper horizontal wall of said receptacleand within said receptacle; a heat-conductive metallic element connecting said heat-'abso'rbing element with said supporting element; aii opening in said receptacle and a closure therefor, said opening arranged to permit the introduction of said refrigerant onto said support by a substantially horizontal movement.

2. A refrigerato'r compr'ising: a receptacle insulated to exclude atmospheric heat; a metallic, fully exposed heat-conductive support for a solid refrigerant located in the lower portion of said receptacle; a wholly metallic and fully exposed heat-absorbing element located in the upper portion of said receptacle and in contact with the air therein, and a heat-conductive metallic ele'- ment connecting said heat-absorbing 'element with said supporting element, said heat-conduC- F ment connecting said heat-absorbing element with said supporting element, and means for interrupting the heat conductivity of said heatconductive connecting element.

4. A refrigerator comprising: a receptacle insulated to exclude atmospheric heat; a heatconductive support for a solid refrigerant located in the lower portion of said receptacle, said support being in the form of a metallic grid and having a header bar; a heat-absorbing element located in the upper portion of said receptacle and in contact with the air therein, and' a heatconductive element connecting said heat-absorbing member with said header bar.

5. A refrigerator comprising: a receptacle insulated to exclude atmospheric heat; a metallic, heat-conductive support for a solid refrigerant located in the lower portion of said receptacle; a heat-absorbing element located in the upper portion of said'receptacle and in contact with the air therein, said element being in the form of a metallic grid and having a header bar, and a heat-conductive element connecting said sup'- port with said header bar.

6. A refrigerator comprising: a receptacle insulated to ex'c'lude atniosp'heric heat; a metaliic, heat-co'nductive support for' a solid refrigerant located in the lower portion of said receptacle; a heat-abs'orbing element located in the upper portion of said receptacle and in contact with the air therein, and a plurality of beat-conductive' metallic elements 'connecting said heat-ab sorbing element'with said supporting element, at least one of the individual connecting elements being provided with means for interrupting its heat cnductivityi 7.' A refngerator comprising: a receptacle in'- sulated to exclude' atmospheric heat; a metallic, heat-conductive support for a solid refrigerant located in the lower portion of said receptacle; a heat-absorbing element composed substantially entirely of a solid metal and locatedin the upper portion of said receptacle,- said element having its metallic surfaces freely eXposed to contact with air currents within said receptacle over substantially its entire area, and heat-conductive means connecting said element with said support.

8. `A refrigerator comprising: a receptacle insulate'd to exclude atmospheric heat; a substantially closed metallic vesse'l adapted to retain solid carbon dioxide, the wall of said Vessl being spaced and insulated from the intefioi" of said receptacle; a heat-absorbing element cemposed substantially entirely of a solid metal and substantially horiz'ontally arranged within said receptacle and adjacent the upper horizontal Wall thereof, the metallic surfaces of said element being freely exposed to contact with the airin said receptacle, and a metallic element connecting said heat-absorbing element with the wall of said' Vessel and ad'aptfed to transmit h'eat from said heat-absorbing element to said carbon dioxide.

9.'A device substantially as and for the purpose set forth in claim 8, including a chamber horizontally arranged above said heat-absorbing element and in heat-conductive relation with the air within said chamber, and means for' cool ing the lower Wall of said chamber' by the p`as-- ment, and means cooperatin'g with said heat-' responsive' means for interrupting and reestablishi'ng the' heat conductivity of said connecting element.

'GO'ITHOLD HARRY MEINZER. 

